I am an absolute newbie to Linux, let alone scripting. I need to compare two images without re-sizing them, and output should be used by script for the following calculations (that is I don’t need to see the difference visually).

A relevant example I found is:

compare -metric MAE image1 image2 null: 2>&1

I changed it to:

compare -metric MAE rose1.jpg rose2.jpg null: 2>&1 (I have no idea what ‘null: 2>&1′ means, would be grateful if you could explain it),

but I got an error – cannot find the files or they don’t exist. Is it because I need to specify full path to the images? or something else is wrong in this script?